Flattened collapsible vascular catheter

ABSTRACT

An apparatus and method for establishing a collapsible infusion conduit in a blood vessel includes a catheter formed as a normally-flattened tube of flexible, collapsible plastic. When placed in a blood vessel, the catheter collapses to a flattened configuration for lying along the wall of the blood vessel to avoid obstruction to blood flow. During infusion, infusion fluid expands the catheter to a generally oval flow path. The catheter may be initially placed in the blood vessel by pre-loading the catheter over a guide wire and inserting the catheter and guide wire through an introducer sheath into the blood vessel. Infusion fluid is thereafter applied to the trailing end of the catheter to expand the catheter to facilitate withdrawal of the guide wire. Alternatively, the leading end of the catheter may initially be sealed, and placement into the blood vessel is achieved through an introducer sheath by inflating the catheter with pressurized fluid to temporarily render the catheter rigid and generally oval. The seal at the leading end of the catheter is thereafter opened, either by inserting a guide wire into the catheter to pierce the sealed end, or by increasing the inflation pressure to burst a weakened break line formed at the leading end of the catheter.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to catheters inserted into thevascular system for extended periods of time, and more particularly, toa collapsible catheter for insertion into a blood vessel, and methodsfor placing such collapsible catheter into the blood vessel.

2. Description of the Related Art

Insertion of catheters into the vascular system of humans and animals isa commonly performed procedure. These catheters function as a conduitfor infusion of fluids or drugs. When a catheter needs to be in placefor greater than three or four days, it is common to place a so-calledcentral line catheter, and to locate the leading tip of the catheter inone of the major veins at the top of the chest leading to the heart,such as the subclavian vein or the major veins of the mediastinum. Insome instances, but less commonly, catheters are passed from the lowerhalf of the body into the inferior vena cava. Central catheters areusually passed into the subclavian vein, jugular vein, or into anantecubital vein at the elbow. Such central catheters may have single ormultiple lumens, and are typically made from a relatively rigid plasticmaterial with a standard, round cross-section, both to facilitateplacement of the catheter into the vein and to prevent the catheterlumens from collapsing within the vein. Generally speaking thesecatheters are constructed in such a way that the lumen or lumensextending therethrough retain their cross-sectional configuration unlessan external mechanical force compresses the catheter.

A complication of placing a central line catheter is the formation ofclots on the wall of the catheter located in the vascular system. Bloodclots form for several reasons. The presence of any object occupyingspace within a blood vessel causes turbulence and slowing of the bloodflow through the vessel, and these factors induce the formation ofclots. Generally, the greater the cross-sectional area of the catheterrelative to the blood vessel, the greater the induced turbulence andslowing of the blood. In addition, the catheter is a foreign body, andthe surface of the catheter in contact with blood acts as a nidus forclot formation. Once again, the greater the amount of surface area ofthe catheter or other foreign body in contact with the blood, the morelikely that clots will form.

Such clots can break away and flow in the blood stream to the heart andlungs, causing severe complications. Furthermore, the formation of clotscan often cause such veins to become irreversibly damaged and thrombose,preventing further blood flow through such veins. This may ultimatelycause debilitating swelling of the limb being drained by these veins.

Apart from the risks of forming clots within the blood vessel, presentcentral line catheters also suffer from susceptibility to clottingwithin the catheter itself. In this regard, blood enters the lumen ofthe catheter and forms a clot within the lumen, obstructing the passageof fluids through the catheter into the vein, and thereby rendering itunusable. While such clots may not be life threatening to the patient,blockage of the catheter can require removal and replacement of thecatheter, a procedure which poses an inconvenience to both the patientand the attending physician, and adds to the cost of maintaining venousaccess.

U.S. Pat. No. 5,176,659 issued to Mancini discloses an expandableintravenous catheter which has a lesser diameter during insertion into avein, and which is thereafter expanded following placement to a largerdiameter. While such device simplifies insertion of the catheter, itstill maintains a sizable obstruction within the vein with a significantexposed surface area, and it still permits blood to enter the lumen ofthe catheter in the absence of fluid flow.

U.S. Pat. No. 5,106,368 to Uldall et al. discloses a dual lumen catheterfor vascular access. The distal portion of the catheter includes twotubular members attached to each other, only one of which is collapsibleThe catheter is inserted into a blood vessel through a peel-away sheath,and over both a stiffening cannula and a guide wire. The collapsiblelumen returns to its original circular shape once placed in the bloodvessel. Thus, no reduction of the cross-sectional area, or surface area,of the catheter is achieved after the catheter is placed. In addition,blood can still enter both lumens of the catheter in the absence offluid flow.

U.S. Pat. No. 4,406,656 issued to Hattler et al. discloses a multi-lumencatheter adapted to be inserted through the center of an insertionneedle into the vein of a patient. The catheter disclosed by Hattler etal. includes two or more collapsible lumens formed around a flexible,but non-collapsible, central lumen. The collapsible lumens expandoutwardly under the pressure of fluid flow and collapse to a smallercross-sectional area in the absence of fluid flow. However, the centrallumen of the Hattler et al. device is formed of materials which retainthe shape of the central passageway whether or not fluids flowtherethrough. Thus, even when the collapsible lumens are collapsed, thedevice disclosed by Hattler et al. still approximates thecross-sectional area of a conventional single lumen catheter. Indeed,Hattler et al. state that the central lumen of the disclosed multi-lumencatheter requires a certain degree of stiffness or rigidity to providesufficient structural support so that the catheter can be handled as areconventional catheters. While the device disclosed by Hattler et al.somewhat reduces the cross-sectional area of a multi-lumen catheter, itdoes not reduce the cross-sectional area or surface area of the catheterbelow that of a conventional single lumen catheter, nor does it preventblood from entering the central, non-collapsible lumen in the absence offluid flow.

Accordingly, it is an object of the present invention to provide acentral line catheter which reduces the likelihood of the formation ofclots within the blood vessel into which the catheter is placed.

It is another object of the present invention to provide such a catheterwhich presents a minimal cross-section obstruction to the normal flow ofblood within the blood vessel when the catheter is not being used forinfusion, while providing a satisfactory flow path to infused fluidsduring infusion procedures.

It is still another object of the present invention to provide such acatheter which minimizes the surface area of the catheter exposed to theblood when infusion procedures are not being performed.

It is a further object of the present invention to provide such acatheter which minimizes the likelihood of blood entering the lumen ofthe catheter and forming a blockage therein.

A still further object of the present invention is to provide a methodfor conveniently placing such a catheter within the desired blood vesselusing commonly available vascular apparatus.

These and other objects of the present invention will become moreapparent to those skilled in the art as the description of the presentinvention proceeds.

SUMMARY OF THE INVENTION

Briefly described, and in accordance with the preferred embodimentsthereof, the present invention is a collapsible vascular infusioncatheter apparatus for providing an infusion passage into a blood vesselwhile occupying minimal space, and presenting minimal surface areawithin the blood vessel, when infusion is not being conducted. Thecatheter of the present invention includes at least first and secondelongated, generally flattened strips of flexible material; suitableflexible material include without limitation plastic sheets formed ofpolyethylene, polyethylene teraphthalate, and polyvinyl chloride. Therespective sides of the first and second strips are joined with eachother to form an elongated, normally-flattened tube having an innerlumen and having first and second opposing ends. The first, or trailing,end of the tube is adapted to receive fluid to be infused into a bloodvessel of a patient, and the second, or leading, end of the tubeprovides an exit port through which fluid received at the first end ofthe tube can be introduced into a blood vessel of a patient.

The normally-flattened tube expands toward a generally oval shape,depending upon the rate of infusion, when fluid is infused into a bloodvessel of a patient, thereby providing an open path for the infusionfluid. When the infusion procedure is terminated, the tube collapsesback to a generally flattened configuration for lying adjacent a wall ofthe blood vessel. In this manner, the tube presents minimalcross-sectional obstruction to the flow of blood within the bloodvessel, and also presents minimal surface area exposed to the bloodflowing in the blood vessel. In addition, the tube acts like a valve bysealing the tip of the tube when the tube collapses to prevent bloodfrom entering the lumen of the catheter.

The preferred embodiment of the above-described catheter includes aradiopaque marker to allow the catheter to be viewed by X-ray orfluoroscope to ensure that the catheter has been positioned within theselected blood vessel as desired. This radiopaque marker may take theform of a radiopaque stripe applied to one face of the tube, aradiopaque marker located at the leading end of the tube, or aradiopaque wire extending along one seam of the catheter.

Alternate embodiments of the present invention include similarlycollapsible catheters having two or more lumens formed therein. Forexample, a second lumen may be provided by including a third elongated,generally flattened strip of the same flexible material extendinggenerally along at least one of the first and second strips, and joiningthe respective sides of third strip with those of the first and/orsecond strips to form a second elongated, normally-flattened tube havinga second lumen in parallel with the first lumen.

In order to facilitate handling of the first, or trailing, end of thecatheter after placement, and to prevent unintended damage to the tubeat the skin entry point, the first end of the tube may include a morerigid skin entry portion extending from the hub of the catheter to theentry point of the blood vessel.

Another aspect of the invention relates to the apparatus and method forplacing the catheter within the patient's blood vessel. One suchprocedure uses a cylindrical guide wire initially extending through thelumen of the normally-flattened tube to rigidify the tube and to shapethe tube into a generally oval shape for insertion into a blood vesselof the patient. The catheter is pre-loaded over the guide wire prior toinsertion, with the tip portion of the guide wire extending through andbeyond the exit port of the tube. An entry path is established throughthe patient's skin into a blood vessel, as by placing an introducersheath using standard angiographic techniques. The guide wire and theleading end of the tube are inserted as a unit through the entry pathand into the blood vessel. The catheter and guide wire are advancedtogether through the blood vessel to a desired location usingfluoroscopic, ultrasonic, or X-ray guidance.

Following insertion in the manner described above, the introducer sheathis removed (assuming that one was used), while temporarily leaving boththe guide wire and catheter in place. The guide wire is then removedfrom the tube while leaving the second, or leading, end of the tubewithin the blood vessel at the desired location and allowing theinserted portion of the tube to collapse against the wall of the bloodvessel. To facilitate the release of the guide wire from the lumen ofthe tube, the present invention may include a mechanism for temporarilyinfusing fluid into the first, or trailing, end of the tube while theguide wire is present within the catheter for expanding the tube. Theinfused fluid expands the tube, freeing the tube from the guide wire,thereby allowing the guide wire to be more easily withdrawn by pullingthe same from the first end of the tube.

An alternate procedure for placing the collapsible catheter of thepresent invention in a selected blood vessel involves the initialformation of a seal at the second, or leading, end of the tube forallowing the tube to be inflated by fluid under pressure. The sealinitially formed at the second end of the tube is adapted to be brokenfor providing the exit port. After establishing an entry path throughthe patient's skin into the blood vessel, an introducer sheath isinserted through the entry path and into the blood vessel. Theintroducer sheath provides an entry passageway into a blood vessel intowhich the tube is to be placed. Next, a device for applying a fluidunder pressure, such as a syringe, is releasably coupled to the firstend of the normally-flattened tube to rigidify the tube and totemporarily form the tube into a more oval shape to facilitate passageof the tube through the introducer sheath for placement within the bloodvessel. The leading end of the tube is then inserted into the introducersheath and into the blood vessel while maintaining the fluid within thetube under pressure. Once the catheter has been advanced to the desiredlocation using fluoroscopic, ultrasonic, or X-ray guidance, theintroducer sheath is removed from the entry path while leaving the tubewithin the blood vessel.

Before the catheter placed in the above-described manner can be used,the seal initially formed at the second end of the tube must first bebroken for allowing fluid within the tube to exit into the blood vessel.In one embodiment of the present invention, a seal-breaking apparatus isinserted into the tube after the syringe or other pressure applicationmechanism is removed. The seal-breaking apparatus is extended along thelength of the tube to a point proximate the second end of the tube foropening the seal at the second end of the tube. Such a seal-breakingapparatus may include a simple guide wire which is inserted into thetube along the length of the tube to a point proximate the second end ofthe tube for piercing the second end of the tube.

In another embodiment of the present invention, the seal formed at thesecond end of the tube is broken remotely by further increasing theinflation pressure applied to the tube. In this embodiment, the sealinitially formed at the second end of the tube includes a weakened breakline that ruptures when fluid pressure within the tube exceeds apredetermined value. During placement of the catheter into the bloodvessel through the introducer sheath, the fluid pressure is maintainedbelow this predetermined value to avoid premature rupture of the seal.Once the catheter is properly placed, the fluid pressure is increased upto the predetermined burst value to rupture the seal along the weakenedbreak line for providing the exit port.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a collapsible venous infusion catheterin accordance with a first embodiment of the present invention.

FIG. 2 is a partial perspective view of the collapsible catheter shownin FIG. 1 with an attached guide wire diaphragm having a side-mountedinfusion port.

FIG. 3A is a cross-sectional view of the collapsible catheter of FIG. 1in its collapsed condition.

FIG. 3B is a cross-sectional view of the collapsible catheter shown inFIG. 1 in its expanded condition.

FIG. 3C is a cross-sectional view of the collapsible catheter shown inFIG. 1 taken through the plane designated by lines 3C in FIG. 1.

FIG. 3D is a cross-sectional view of the collapsible catheter collapsedagainst the surrounding wall of a blood vessel into which the catheterhas been placed.

FIG. 4 is a cross-sectional view of the infusion end of the collapsiblecatheter, and related guide wire diaphragm/infusion port taken throughthe plane indicated by line 4 in FIG. 2.

FIG. 5 is an exploded perspective view of the guide wirediaphragm/infusion port shown in FIGS. 1 and 2.

FIG. 6 is a perspective view of the second, or leading, end of thecollapsible catheter, and including a radiopaque stripe and a weakenedbreak line.

FIG. 7 is a cross-sectional view of the forward tip of the collapsiblecatheter shown in FIG. 6 viewed through the plane designated by lines 7within FIG. 6.

FIG. 8A is a partially sectioned view of a patient's vein lying belowthe skin, and illustrating the placement of a peal-away introducersheath along the entry path into the vein.

FIG. 8B illustrates the introducer sheath within the patient's veinfollowing removal of its accompanying dilator.

FIG. 8C is a perspective view of a syringe coupled to the trailing endof the collapsible catheter.

FIG. 8D is a sectional view of the tip of the collapsible catheter andshowing the tip of a guide wire inserted into the collapsible catheterand about to pierce the sealed leading end thereof.

FIG. 8E illustrates the entry of the second, or leading, end of thecollapsible catheter into the introducer sheath.

FIG. 8F illustrates the inflated collapsible catheter followinginsertion through the introducer sheath.

FIG. 8G illustrates the collapsible catheter following removal of thesheath, and immediately following bursting of the initially sealed tipof the catheter.

FIG. 9A illustrates a cross-sectional view of the collapsible catheterand supporting guide wire, as shown in FIG. 1, immediately followingplacement of the catheter into a vein.

FIG. 9B is a cross-sectional view of the collapsible catheter andsupporting guide wire after infusing fluid into the catheter forallowing the guide wire to be withdrawn.

FIG. 10 is a side view showing a portion of syringe coupled to theside-mounted infusion port of the guide wire diaphragm device forinfusing fluid into the collapsible catheter to free the guide wire fromthe walls of the catheter.

FIG. 11 is a cross-sectional view of a dual lumen collapsible catheterconstructed in accordance with the teachings of the present invention,supported by a stiffening guide wire, and including a radiopaque markingwire.

FIG. 12 is a triple lumen collapsible catheter constructed in accordancewith the teachings of the present invention and including a supportinginsertion guide wire.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a first embodiment of a fully-collapsible venousinfusion catheter apparatus for providing an infusion passage into avein in accordance with the teachings of the present invention. Whilethe preferred embodiment of the present invention described herein isplaced in a vein, the present invention is not intended to be limited touse with veins, but should be understood to extend to any blood vessel.The collapsible catheter is designated generally by reference numeral 20within FIG. 1, and includes a leading open end 22 and an opposingtrailing end 24. Leading end 22 provides an exit port through whichfluid received at trailing end 24 can be introduced into a vein of apatient. Trailing end 24 terminates in a conventional rigid plastic body26 having a knurled collar or hub 28 to facilitate handling. Aconventional luer lock connector fitting 30 is provided at the end ofbody 26 for connection to syringes, infusion lines and the like forreceiving fluid to be passed through catheter 20 to exit port 22.

Referring to FIG. 3A and 3B, the collapsible portion of catheter 20includes a first elongated, generally flattened strip 32 of flexiblematerial having first and second opposing sides 34 and 36. First strip32 extends the length of catheter 20 from trailing end 24 to leading end22. The collapsible portion of catheter 20 also includes a secondelongated, generally flattened strip 38 of flexible material havingfirst and second opposing sides 40 and 42, and like first strip 32,extends the length of catheter 20 from trailing end 24 to leading end22. First side 40 of second strip 38 is joined with the first side 34 offirst strip 32; likewise, second side 42 of second strip 38 is joinedwith the second side 36 of first strip 32 to form an elongated,normally-flattened, collapsible tube 44 having opposing ends 22 and 24.

Tube 44 is shown in its collapsed configuration in FIG. 3A prior toplacement in a vein. Within FIG. 3D, tube 44 is shown collapsed againstthe inner wall of vein 46 following placement in the vein, and in theabsence of fluid flow therethrough. This is the configuration which theinventor anticipates tube 44 will assume in the vein in the absence ofthe flow of infusion fluid therethrough. In this collapsedconfiguration, tube 44 occupies minimal space within the vein wheninfusion is not being conducted, and therefore causes minimal turbulenceand slowing of blood flow within vein 46. In addition, because almostone-half of the surface of tube 44 lies adjacent the wall of vein 46when in the collapsed condition shown in FIG. 3D, the amount of surfacearea of tube 44 exposed to blood flow within vein 46 is minimized. Allof these features lessen the likelihood of blood clot formation withinvein 46. In addition, since exit port 22 of tube 44 also assumes thecollapsed configuration shown in FIG. 3D in the absence of fluid flow,blood is prevented from entering the lumen of tube 44 between infusionprocedures, thereby lessening the possibility for clots to form withinthe lumen, and the resulting blockage of infusion fluid. Thus, thecollapsible leading end of tube 44 functions like a one-way flap valveto permit infusion fluid to escape therefrom and to prevent blood fromentering therein.

As shown in FIGS. 3B and 9B, tube 44 can be expanded by infusing fluidthrough tube 44. The normally-flattened tube 44 expands to a generallyoval shape when fluid is infused into a vein of a patient, therebyproviding a sizable cross-sectional path for fluid to be passed into thevein. When infusion is terminated, tube 44 collapses back to thegenerally flattened configuration shown in FIG. 3D for lying adjacentthe wall of the vein.

While strips 32 and 38 have been described as discrete strips joinedalong their respective sides, it should be understood that strips 32 and38 may be integrally formed with each other, and that the describedjoinder of the side edges of such strips may, in fact, constitute theformation of pleats or folds in what is otherwise a single, smoothcontinuous surface. Suitable materials for forming strips 32 and 38include strong but flexible plastic films, including those made ofpolyethylene, polyethylene teraphthalate, and polyvinyl chloride. In thepreferred embodiment of the present invention, these plastic films areinelastic, although plastic films which exhibit elasticity might also beused.

Referring back to FIG. 1 tube 44 includes a skin entry portion 48extending adjacent trailing end 24 of tube 44, and adjacent hub 28; thisskin entry portion ultimately extends through the skin of the patient atthe point of entry following placement of the catheter. If desired, thisskin entry portion 48 of tube 44 may be made relatively rigid for alength of approximately eight to ten centimeters, as measured from hub28, to facilitate handling of the catheter by medical personnelfollowing placement, and to prevent damage to catheter 20 from long termmanipulation.

As noted above, it is desired to make the majority of tube 44 that lieswithin the vein fully collapsible. However, a catheter that has norigidity is almost impossible to insert into a vein as compared with acatheter which has rigidity. Accordingly, another aspect of the presentinvention relates to the apparatus and method used to place such a fullycollapsible catheter within a vein. One such apparatus and method isshown in FIGS. 1 and 3C, wherein catheter 20 is pre-loaded onto acylindrical guide wire 50 that initially extends throughnormally-flattened tube 44 to rigidify tube 44 and to temporarily shapeit into a generally oval shape for insertion into the vein of a patient.As used in this specification and within the claims which follow, theterm generally-oval should be understood to include cylindrical shapes.FIGS. 3C, 9A, and 9B illustrate the space within tube 44 surroundingguide wire 50 as being relatively large for clarity and to simplify thedrawings. In practice, the inventor anticipates that guide wire 50 wouldclosely approximate the internal "diameter" of tube 44, therebyproviding a relatively close fit between tube 44 and guide wire 50 toavoid bunching of tube 44 along guide wire 50 during insertion. Guidewire 50 has a tip portion 52 which extends through and beyond exit port22 of tube 44 during insertion.

Prior to insertion of catheter 20 and guide wire 50 into the vein of thepatient, a guide wire diaphragm/side infusion port device 54 is slidover the trailing end of guide wire 50, as shown in FIG. 1. As shownbest in FIGS. 4 and 5, device 54 includes a split seal diaphragm 56secured thereto by a threaded cap 58 having a central bore 60 formedtherein. Guide wire 50 extends through bore 60 and is wipingly engagedby split seal diaphragm 56 to prevent the loss of blood or infused fluidaround guide wire 50. Device 54 also includes a side port 62 which ispreferably provided with a luer lock connector fitting 64 for receivinga syringe or other source of infusion fluid. As shown in FIGS. 2 and 4device 54 also includes a luer lock fitting 65 which is engaged withmating luer lock fitting 30 of catheter 20 to form a fluid tight sealtherebetween.

Next, an entry path is established through the skin. Such an entry pathmay be established, by way of example, using the Seldinger technique ormodified Seldinger technique, both of which are well known to thoseskilled in the art. For example, using the modified Seldinger techniquean introducer sheath is inserted through the skin into the vein,providing a convenient passage for inserting the guide wire 50 andcatheter 20, as a unit, into the vein. Proper placement of the leadingend 22 of the catheter can be confirmed using X-rays, fluoroscopy, orultrasound provided that a radiopaque marker stripe 66, like that shownin FIGS. 6 and 7, is formed upon and along one of flattened strips 32 or38 of tube 44. Alternatively, a radiopaque wire 68 can be incorporatedwithin a seam or pleat of tube 44 for extending along the tube, as shownin FIG. 11.

Once proper placement of the catheter tip is confirmed, guide wire 50 isremoved. However, as shown in FIGS. 3C and 9A, guide wire 50 closelyapproximates the internal diameter of tube 44, and excessive frictionbetween guide wire 50 and tube 44 could dislodge tube 44 from itsdesired position within the vein and/or cause kinks in catheter 20.Accordingly, prior to removal of guide wire 50, a syringe 70 or othermechanism for injecting a fluid is coupled to side port 62 of diaphragmdevice 54, as shown in FIG. 10, for injecting fluid into the lumen oftube 44. As indicated in FIG. 9B, the injected fluid 72 further expandstube 44 and moves the internal walls thereof away from guide wire 50while additionally lubricating guide wire 50, thus allowing guide wire50 to be withdrawn from catheter 20 without dislodging catheter 20within the vein or creating kinks therein. Upon removal of guide wire50, device 54 is removed from luer lock connector fitting 30 of catheter20. Tube 44 then collapses against the wall of the vein, as shown inFIG. 3D, until an infusion procedure is initiated.

A second method of rigidifying the catheter for insertion avoids theneed for a guide wire and instead uses a pressurized fluid to inflatetube 44 for purposes of insertion. This second method requires that theleading end 22 of catheter 20 is initially sealed, as shown in FIGS. 6and 7, rather than being open as described with respect to FIG. 1. Asshown in FIGS. 6 and 7, leading end 22 of tube 44 is initially sealed,but the seal formed at the second end of tube 44 preferably includes aweakened break line 74 which is adapted to be broken for providing anexit port. As described in greater detail below, this seal is laterbroken either locally or remotely after the catheter is properly placed.

Prior to placement of catheter 20 using the pressurized fluid method, anintroducer sheath is inserted into the vein, in the manner shown in FIG.8A. The introducer sheath includes a stiffening dilator 76 and apull-apart sheath 78. The introducer sheath assembly is itself guidedinto vein 46 over a guide wire (not shown). As indicated in FIG. 8B, therigid dilator 76 is then removed, leaving the pull-apart sheathextending through the skin 47 and into vein 46, thereby providing anentry passageway into a vein into which tube 44 is to be placed.

The next step is to pressurize tube 44 with fluid to rigidify tube 44and make it more oval. As indicated in FIG. 8C, an angiographic syringe80 filled with contrast dye is releasably secured to luer lock fitting30 of catheter 20, and the plunger of syringe 80 is depressedsufficiently to inflate tube 44 with contrast dye fluid. The materialssuggested above for use in forming tube 44 are easily capable ofwithstanding a pressure of 5 Atmospheres without bursting, and suchpressure is adequate to temporarily rigidify tube 44 for placementwithin the vein. While not illustrated, syringes which include pressuregauges are available and well known to those physicians practicing inthe art. As indicated in FIGS. 8E and 8F, tube 44 of catheter 20 is theninserted into sheath 78 and advanced therethrough into vein 46 untilsealed end 22 is positioned at a desired location within the vein, whilemaintaining pressure on the fluid within the tube. The presence of thecontrast dye within tube 44, and the radiopaque markings on the tube,allows the catheter to be visible in X-rays or on a fluoroscope.

After properly positioning catheter 20, pull-apart sheath 78 iswithdrawn from the entry path while leaving tube 44 within the vein.FIG. 8F shows catheter 20 within vein 46 following removal of sheath 78but before pressure has been released from tube 44. The final step is tobreak the seal at the seal at the leading end 22 of tube 44 for allowinginfusion fluid within the tube to exit into the vein. Two preferredmethods of breaking the seal will now be described.

In the first seal breaking method, syringe 80 is removed from luer lockconnector 30 of catheter 20, and a seal-breaking apparatus is insertedinto tube 44 along the length of the tube to a point proximate leadingend 22 of the tube for opening the seal therein. For example, as shownin FIG. 8D, the so-called seal-breaking apparatus consists of a guidewire 82 inserted into tube 44 along the length of the tube to a pointproximate leading end 22; the leading tip portion of guide wire 82 isadvanced into the sealed end of tube 44 for piercing the sealed end ofthe tube to create the exit port.

The second method for breaking the seal at the leading end of tube 44,after the tube is properly positioned within the vein, involves raisingthe fluid pressure within tube 44 beyond the burst strength of theweakened break line at the second end of the tube. As mentioned above,syringe 80 (see FIG. 8C) normally applies no more than 5 Atmospheres ofpressure to the contrast fluid dye in tube 44 during insertion ofcatheter 20 to avoid premature rupture of the seal. However syringe 80is capable of applying at least 10 Atmospheres of pressure to thecontrast dye fluid injected into tube 44. This higher pressure isadequate to rupture the seal along the weakened break line 74 at leadingend 22 of tube 44 for providing the exit port. Confirmation of thesuccessful rupture of the seal using this method can be confirmed usinga fluoroscope by observing a puff of contrast dye emitted from the tipof the catheter.

While the embodiments of the invention described thus far provide acatheter having only a single lumen, a fully collapsible multi-lumencatheter may also be constructed in accordance with the teachings of thepresent invention. Referring to FIG. 11, a third elongated, generallyflattened strip 84 of the same flexible material as strips 32 and 38 canbe secured along its side edges with the respective side edges of firststrip 32 to form a second elongated, normally-flattened tube in parallelwith tube 44; the collapsed lumen of such second tube is designated inFIG. 11 by reference numeral 86. The original lumen of the firstnormally-flattened tube is pre-loaded upon guide wire 50, as shown inFIG. 11, prior to insertion into the vein. The third strip 84 may, ifdesired, be made of the same length as strips 32 and 38 to provide asecond lumen 86 having an exit port at its leading end disposed atapproximately the same point in the vein as the exit port of the firstlumen. Alternatively, third strip 84 may be made shorter in length thanstrips 32 and 38 to create a shorter second lumen 86 having an exit portthat is longitudinally displaced from the exit port of the first lumen.Each of the two tubes may be provided with its own catheter hub (notshown) at the trailing end of such tubes in order to allow for separatecontrol over the fluids infused therethrough.

Likewise, in FIG. 12, a fourth elongated, generally flattened strip 88of the same flexible material as strips 32, 38, and 84 can be securedalong its side edges with the respective side edges of second strip 38to form a third elongated, normally-flattened tube in parallel with tube44; the collapsed lumen of such third tube is designated in FIG. 12 byreference numeral 90. The above-described insertion methods for catheter20 apply equally well to the double and triple lumen catheters shown inFIGS. 11 and 12 respectively.

Those skilled in the art will now appreciate that an improved, fullycollapsible venous infusion catheter has been described which presentsminimal obstruction to blood flow within a vein, which presents minimalsurface area in contact with blood flowing in the vein, and whichprevents blood from entering the infusion lumen between infusion cycles,yet which expands to provide a relatively large infusion path duringinfusion procedures. While the present invention has been described withrespect to several preferred embodiments thereof, such description isfor illustrative purposes only, and is not to be construed as limitingthe scope of the invention. Various modifications and changes may bemade to the described embodiments by those skilled in the art withoutdeparting from the true spirit and scope of the invention as defined bythe appended claims

I claim:
 1. Collapsible vascular infusion catheter apparatus forproviding an infusion passage into a blood vessel while occupyingminimal space within the blood vessel when infusion is not beingconducted, said catheter comprising in combination:a. a first elongated,generally flattened strip of flexible material having first and secondopposing ends and having first and second opposing sides; b. a secondelongated, generally flattened strip of flexible material having firstand second opposing ends and having first and second opposing sides, thefirst side of said second strip being joined with the first side of saidfirst strip, and the second side of said first strip being joined withthe second side of said second strip to form an elongated,normally-flattened tube having opposing leading and trailing ends; c.the trailing end of said tube being adapted to receive fluid to beinfused into a blood vessel of a patient; d. the leading end of saidtube providing an exit port through which fluid received at the trailingend of said tube can be introduced into a blood vessel of a patient; e.said normally-flattened tube expanding to a generally oval shape whenfluid is infused into a blood vessel of a patient, and collapsing backto a generally flattened configuration when infusion is terminated forlying adjacent a wall of the blood vessel.
 2. The apparatus recited byclaim 1 further including a cylindrical guide wire initially extendingthrough said flattened tube to rigidify said tube and to shape said tubeinto a generally oval shape for insertion into a blood vessel of apatient, said guide wire having a tip portion, and the tip portion ofsaid guide wire extending through and beyond the exit port of said tubeduring insertion.
 3. The apparatus recited by claim 2 including infusionmeans for infusing fluid into the trailing end of said tube while saidguide wire extends therethrough for expanding said tube to allow saidguide wire to be withdrawn therefrom.
 4. The apparatus recited by claim1 further including a guide wire having a leading tip portion adapted tobe inserted into the trailing end of said tube and advanced along saidtube after said tube is placed in a blood vessel, and wherein theleading end of said tube is initially sealed, and wherein the sealformed at the leading end of said tube is adapted to be broken by theleading tip portion of said guide wire after said tube is placed in ablood vessel for providing said exit port.
 5. The apparatus recited byclaim 1 wherein said tube initially has a seal formed at the leading endthereof, the seal formed at the leading end of said tube being adaptedto be broken for providing said exit port, said apparatus including anintroducer sheath for providing an entry passageway into a blood vesselinto which said tube is to be placed, said apparatus further including ameans releasably coupled to the trailing end of said tube for applying afluid under pressure into said tube to inflate and rigidify said tube tofacilitate passage of said tube through said introducer sheath forplacement within the blood vessel.
 6. The apparatus recited by claim 5further including a guide wire having a leading tip portion adapted tobe inserted into the trailing end of said tube and advanced along saidtube to open the seal formed at the leading end of said tube after saidtube is placed in a blood vessel, and after said pressure applicationmeans is removed from the trailing end of said tube.
 7. The apparatusrecited by claim 5 wherein the seal formed at the leading end of saidtube includes a weakened break line that ruptures when fluid pressurewithin said tube exceeds a predetermined value, said pressureapplication means being adapted to apply a first fluid pressure belowsaid predetermined value during placement of said tube through saidintroducer sheath and into the blood vessel to avoid premature ruptureof the seal, said pressure application means being adapted to apply asecond fluid pressure equal to said predetermined value followingplacement of said tube into the blood vessel to rupture the seal alongsaid weakened break line for providing said exit port.
 8. The apparatusrecited by claim 1 wherein at least one of said elongated, generallyflattened strips of flexible material includes a radiopaque stripeextending therealong for allowing the position of the tube to beradiographically viewed within the blood vessel.
 9. The apparatusrecited by claim 1 further including a radiopaque wire extending withinand along said normally flattened tube for allowing the position of thetube to be radiographically viewed within the blood vessel.
 10. Theapparatus recited by claim 1 further including a third elongated,generally flattened strip of flexible material having first and secondopposing sides, the third strip extending generally along said first andsecond strips, the first side of said third strip being joined with thefirst side of one of said first and second strips, and the second sideof said third strip being joined with the second side of one of saidfirst and second strips to form a second elongated, normally-flattenedtube having opposing leading and trailing ends, said first and secondnormally flattened tubes providing first and second lumens of a plurallumen catheter.
 11. The apparatus recited by claim 1 wherein thetrailing end of said tube includes a catheter hub, the trailing end ofsaid tube further including a skin entry portion extending from said hubfor passing through the patient's skin and being relatively rigid forpreventing damage to said tube arising from long term manipulation ofsaid catheter following placement.
 12. The apparatus recited by claim 1wherein said first and second elongated, generally flattened strips offlexible material are made of plastic.
 13. The apparatus recited byclaim 12 wherein said plastic is selected from the group of plasticsconsisting of polyethylene, polyethylene teraphthalate, and polyvinylchloride.
 14. The apparatus recited by claim 12 wherein said plastic isinelastic.